[R] Increase the size of the boxes but not the text in a legend

[Jürgen Biedermann]

HI there,

I want to add a legend to a plot using the density and angle argument, 
so patterns with lines in different angles are used in the plot and 
should be referred to.
When I use default settings, the filled boxes are too small.
With the cex argument I can enlarge the whole legend, but then the text 
gets too big.

How could I just increase the size of the single boxes and not the text.

I tried:

legend("topright", c("Trefferquote","Falschalarmquote"), 
density=c(20,16), angle=c(45,0),cex=1.5, y.intersp=0.8)

The sizes of the boxes are good now, but the text is too large and so 
also the whole legend box gets too big.

Thank you very much for your help
Jürgen